Mixed Carbazole Self-Assembled Monolayers Enable Scalable Large-Area (>5 cm2) Efficient Wide Bandgap Perovskite Solar Cells
Venkatesh G. Chityala, Chander Mohan, Chinmaya Kumar Sahoo, Ravi Prakash Rao, Deepika Choudhary, Anas M. M., Abhijit Singha, Ajay Kumar, Tulsiram Moodalabeed Prasannakumar, Sudhanshu Mallick, Anil Kottantharayil, Kavaipatti Ramanathan Balasubramaniam, Pradeep R. Nair, Dinesh KabraAbstract
Scalability and operational stability remain critical challenges for wide-bandgap perovskite solar cells (PSCs). Here, we report a mixed self-assembled monolayer (SAM) based on a carbazole moiety as a hole transport layer (HTL) to enable large active area (>5 cm2) PSC fabrication. Buried-interface reveals a compact grain size, reduced pinholes, and enhanced large-area film homogeneity of perovskite films prepared on mixed SAM. Top photoluminescence (PL) study show a recombination exponent (k) of 1.175 for the mixed-SAM HTL/perovskite films, indicating suppressed non-radiative losses. Optimized small-area devices (1.2 cm2) achieve a power conversion efficiency (PCE) of 20.30%, with an open-circuit voltage (VOC) of 1.204 V and fill factor (FF) of 81.32%, alongside enhanced damp-heat stability (T75 > 680 h). Voltage and FF losses are analyzed via transient PL based analytical model and empirical FF model, respectively. Upon scaling to 5.2 cm2, a PCE of 18.88% was maintained with only ∼7% relative efficiency loss majorly associated with reduced FF due to increased series resistance with increased area by almost 433% of the transparent conducting oxide substrate. These results establish mixed-SAM engineering with optimal chemical and electronic properties as an effective route toward scalable, efficient, and stable wide-bandgap PSCs.